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Q:
If a photon has zero rest mass, then how it could have energy in terms of E=MC^2 (M is rest mass). If M is zero then E is also zero. Isn't it this way?
- Indrajit
New Delhi, India
A:
You wrote down only part of the full equation. The correct relation between energy, mass and momentum is E
2 = (mc
2)
2 + (pc)
2, where p is the momentum. So for a zero rest-mass photon it becomes E = pc.
No problem.
Look at
http://en.wikipedia.org/wiki/Mass_in_special_relativity for more information.
LeeH
(published on 05/28/2010)
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